assessing cumulative impacts to wide-ranging species ...€¦ · existing human development...

Assessing Cumulative Impacts to Wide-Ranging Species Across the

Peace Break Region of Northeastern British Columbia

A Summary Report Prepared by Clayton Apps, Ph.D., R.P.Bio.Commissioned by Yellowstone to Yukon Conservation Initiative

(For the full report see www.y2y.net/publications)

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2 Assessing Cumulative Impacts in the Peace Break Region (2014)

Yellowstone to Yukon Priority Areas1. Greater Mackenzie Mountains

2. Upper Liard River

3. Stikine-Nass-Skeena Headwaters

4. Muskwa-Kechika Ecosystem

5. Peace River Break

6. Central Canadian Rocky Mountains

7. Cabinet-Purcell Mountain Corridor

8. Crown of the Continent

9. Salmon-Selway-Bitterroot

10. High Divide

11. Greater Yellowstone Ecosystem


IntroductionIn a world dominated by human activity, the

Rocky Mountain cordillera of North America,

from Yellowstone to Yukon (Y2Y), is composed

largely of wild lands that are relatively intact

to various degrees. One key linkage in the

Y2Y region is the Peace River watershed of

northeastern British Columbia, with the river

providing a natural east-west break in the Rocky

Mountain ranges. Known as the Peace Break, this

area is ecologically diverse with a long history of

First Nations use and, later, European settlement

(see Figure 1). In contrast to most other Rocky

Mountain regions, the Peace Break has little

protected area representation and a substantial

existing human development footprint. This,

combined with natural constraints, results in

a critical “pinch-point” in the continuity of

ecologically intact and functioning landscapes

along the north-south extent of the Canadian

Rocky Mountains in the Y2Y region. The

tenuous continuity and unique ecological values

of the Peace Break are potentially threatened

by the “cumulative” impact of rapid industrial

expansion including several major proposed

developments.

Purpose of the AssessmentPopulation connectivity for several wide-ranging

terrestrial species and some aquatic species

is likely to be highly constrained in the Peace

Break region, with the potential for fracture.

This impact could be exacerbated by additional

cumulative effects resulting from current resource

development trends and multiple proposed

major projects, including the proposed Site C

hydroelectric dam and impoundment on the

Peace River.

My report describes an extensive, broad-scale

assessment of cumulative human impacts and

their influence on landscape potential to support

Assessing Cumulative Impacts to Wide-Ranging Species Across the Peace Break Region of Northeastern British ColumbiaA Summary Report Prepared by Clayton Apps, Ph.D., R.P.Bio.

Commissioned by Yellowstone to Yukon Conservation Initiative(For the full report see www.y2y.net/publications)

Figure 1 (opposite): Map of the

Y2Y region with priority areas,

with the Peace Break Region

highlighted in red.

(cover/back photo: Larry

Peterson)

www.y2y.net/publications


wide-ranging terrestrial species across the

Peace Break. Terrestrial species addressed are

associated with a range of ecological conditions

that are broadly represented within the larger

region. There are two parallel and related aspects

to this assessment:

1. Understanding current and potential-future

changes to the ability of specific landscapes to

support defined focal species, and

2. Understanding spatial patterns of population

connectivity that are important in the

long-term stability and resilience of these

species and the ecological communities they

represent.

BackgroundCentral to the Peace Break region of northeastern

BC is the Peace River valley which “breaks”

through the Rocky Mountains and funnels warm,

moist Pacific air east of the Rockies. Owing

to this and other physiographic and climatic

influences, the Peace Break is ecologically diverse,

with inherent variation in the potential for

species occurrence and distribution.

For my analysis, I defined a “regional” assessment

area of 74,325 km2. Within this I embedded a

“local” assessment area of 13,416 km2 defined by

a 25 km buffer surrounding the original course of

the Peace River (see Figure 2).

Both local and regional areas have a long history

of human use. After thousands of years of First

Nations use, European influence began with the

fur trade followed by agriculture and permanent

settlement in the early 1900s. Highways, logging,

oil and gas, and hydroelectric development

continued through the latter part of the century.

Today, many types of human activities emanate

from several major population centres and other

smaller communities. Within the Peace River

Regional District, the resident human population

The Concept of Cumulative Effects

The notion that human environmental and social impacts accrue cumulatively over

space and time stems from the recognition that environmental degradation is largely

due to the “tyranny of small decisions”1. In Canada, cumulative effects assessment

(CEA) was defined in the 1980s as “impacts on the natural and social environment

which occur so frequently in time or so closely in space that they cannot be

assimilated, or they combine with effects of other activities in a synergistic manner2.

Fundamental to the concept of cumulative effects is that the end degradation is greater

than would be expected if impacts were considered individually. For example, species

extirpation (local or extensive) and other population impacts are virtually never tied

to single developments and are always mediated by underlying habitat conditions and

dynamics, whether natural or human-influenced. Essential to managing cumulative

effects is the establishment of common goals and specific thresholds for acceptable

impacts, coordinated among government agencies and jurisdictions3.


grew 6.7% between 2007 and 2011, from 60,220

to 64,2804. To the year 2036, with current

demographic trends, this growth rate is expected

to decline somewhat, but still increase a further

23.5% to 79,3845.

In the mid-twentieth century, four major

hydroelectric dams on the Peace River were

proposed. Two were built while the other two

were rejected in the early 1980s. However,

one dam that was initially rejected has been

resurrected for proposed development. This “Site

C” dam would impound the Peace River and its

tributaries about 7 km southwest of Fort St. John,

flooding 5,550 ha of land.

The Site C development proposal is in the final

stages of a joint federal/provincial environmental

Figure 2: The regional and

local assessment areas defined

for evaluating the cumulative

impact of human activity

on select wide-ranging focal

species.


assessment process. Given the broad range of

existing human activities and associated impacts

within the Peace Break region, cumulative effects

have been raised as an issue in the evaluation

of the Site C development. That is, this major

project should be considered within the context

of a plethora of existing impacts that have and

will continue to accrue over space and time.

For wide-ranging species, regional evaluation of

cumulative effects is especially important since

population viability and stability are greatly

affected by spatial patterns of distribution and

the broad-scale movement of individuals and

their genes. A regional assessment should be

comprehensive with respect to human use, since

the habitat requirements of wildlife species can be

affected by many types of resource development

or other activity. The spatial pattern of impacts

is the key to cumulative effects assessment, since

most species are affected by habitat connectivity

and fragmentation at different scales.

Focal Species ProfilesAside from conservation issues that may be

unique to individual species, wide-ranging

species are appropriate surrogates for the

conservation of biodiversity and associated

natural processes at broad, regional scales. In

modeling for the assessment and mitigation of

cumulative effects, I selected a suite of species

representing the array of regional ecosystem

conditions while also being sensitive in different

ways to human impacts. These focal species are:

grizzly bear, lynx, fisher, wolf, wolverine and

woodland caribou. Since the proposed Site C

development would affect the aquatic ecosystem,

I also considered bull trout and Arctic grayling

though only through qualitative means. For each

species, I profiled ecological requirements, local

knowledge, impacts and threats as well as current

status and conservation.

Evaluating Landscape EffectivenessFor each terrestrial focal species, I evaluated

the potential influence of present and future

Figure 3: Index of human

population access/remoteness

across the Peace Break

assessment area, current (top)

and projected to year 2036

(bottom).


cumulative human impacts on the underlying

potential for landscape-scale habitat effectiveness

and connectivity at the population level. Spatial

modeling was based on the best available

data and current understanding relevant to

predicting species occurrence and distribution

across the Peace Break assessment areas. This

involved assembling GIS coverage from data

sources of climate and physiography, land cover

and vegetation, and human use. From this

spatial database, I derived predictive factors for

modeling species requirements and cumulative

human impacts. Modeling approaches varied

among species, with modeling scales for each

species based on known or expected female core

home range size.

In addition to current habitat conditions and

resulting landscape potential, human accessibility

to the landscape is perhaps the most relevant

predictor of population fragmentation among

wildlife species. To account for cumulative

human influence on each species, I therefore

applied a modeling approach that considers

human travel time to a given site on the

landscape as influenced by biophysical conditions

and human features (such as roads or trails) that

facilitate access and travel speed. The model

accounts for accessibility from any resident

human population and the size of those centres.

Output is interpreted in terms of the ease of

landscape accessibility by, and remoteness from,

people. The derived index of accessibility was

projected into the future (e.g., to year 2036)

given expected demographic trends (see Figure

3). Considering the nature of human impacts

on each focal species, I approximated the shape

of the relationship between human population

access and the potential that each species may

persist and move within or among occupied

Importance of Regional Context

Cumulative Effects Assessment (CEA) is most relevant to comprehensive multi-scale

evaluation within the context of larger population areas, current and projected human

impacts, and changing environmental conditions. This regional approach is especially

important for wide-ranging species given the challenge in balancing their needs

against other multiple resource values. It is unrealistic to expect that meaningful

assessment of impacts to grizzly bears, for example, could be achieved in highly

localized project-specific assessment. Without the regional context, it is difficult

to consider the relevance of localized impacts at the most important, population

level. Further, CEA should ideally be carried out against regional-level thresholds of

acceptable impact. Since no such standards exist in British Columbia as pertaining to

any wide-ranging species, the “significance” of any cumulative impact is impossible to

determine regardless of how large or small a relative change appears to be. The utility

of CEA is thus in comparing among scenarios or in demonstrating the mitigation

necessary to theoretically balance or offset predicted impacts.


landscapes. As translated to mathematical

functions, I applied these curves to the human

accessibility model to approximate the relative

reduction in landscape potential for each species,

termed realized landscape effectiveness.

I compared model outputs among three

scenarios:

1. “Undisturbed” conditions with current land

cover attributes (i.e., vegetation cover and

water surfaces) but no human influence;

2. “Current impact” considering all present

human infrastructure, population and

development (see Figure 4); and

3. “Future year 2036” involving projected

regional population growth given existing.

demographic trends and completion of the

proposed Site C hydroelectric development.

The latter scenario is likely to be a conservative

estimate of future impacts because it cannot

account for all potential future human use and

development, including access infrastructure,

which are impossible to predict. I compared

impacts among these three scenarios, measuring

average landscape effectiveness for each species

(i.e., accounting for human influence) across

defined assessment areas. I also quantified

landscape connectivity for each species by

calculating the area/perimeter ratio of landscapes

that are within four thresholds of landscape

effectiveness. I interpreted impacts based on the

change in both average landscape effectiveness

and associated fragmentation among scenarios.

ResultsResults reflect the differing nature of cumulative

impacts and the potential for landscape

occupancy and connectivity among species, with

significant changes apparent among scenarios.

Absolute reductions in regional landscape

effectiveness among species range from 7% to

47% at present to a projected loss of between 11%

and 55% in 25 years. Within the local assessment

area, the reduction in landscape effectiveness

among species ranges from 13% to 55% at present

to a projected loss of between 19% and 62% in 25

years (see Figure 5). Impacts are compounded by

increased fragmentation that is apparent for most

species at either or both analysis scales. Both the

absolute loss and the fragmentation of landscape

effectiveness can also be qualitatively assessed

through the mapped pattern of modeled species

occurrence and distribution among potential,

realized and future-projected scenarios.

WolfCurrent impacts are greater for species whose

natural distribution is more strongly linked

to lower elevations and/or subdued terrain

conditions. This is especially true for wolves,

which range extensively, tend to conflict with

particular human values and activities such as

agriculture and hunting, and are afforded little

protection outside of certain parks. Despite

these impacts, wolves have persisted due to

their higher resilience than many other wide-

ranging carnivores. At both analysis scales,

total landscape effectiveness for wolves has

been markedly reduced (i.e., 12% loss) and this


is likely to continue into the future (i.e., 22%

loss). Impacts to wolves are exacerbated by the

pattern of fragmentation, whereby current and

future scenarios are associated with substantial

fracturing of the highest quality landscapes,

with increased interspersion of marginal habitat

conditions.

FisherWithin the assessment area, the potential

distribution of fisher habitat also is associated

with landscapes of relatively high overall human

influence. While fishers generally do not conflict

with people, they are potentially vulnerable to

trapping mortality and are thus impacted to some

degree by human accessibility. Fisher habitat

distribution and connectivity also tends to occur

at a finer scale than other wider-ranging species

and particularly in association with riparian areas

with specific attributes of forest composition and

structure.

Fishers are vulnerable to habitat loss and

fragmentation, especially due to complete

alienation such as through forest clearing and

agriculture in addition to flooding for hydro-

electric impoundment. Analysis results suggest

that impacts to fishers are more significant at

the local (13% currently) than the regional scale

(8% currently), likely as a result of the close

association of fisher habitat with landscapes of

current and proposed modification, including

hydroelectric impoundments within the Peace

River valley. While population connectivity is

undoubtedly important in conservation planning

for fishers, the more acute conservation issue

appears to be the absolute loss and alienation of

quality habitat.

Lynx Like fisher, human impacts on lynx are also

primarily by way of increased mortality risk

through legal and illegal harvest. The majority

of lynx harvest in the assessment area is through

trapping. However, human accessibility

potentially impacts lynx more than many other

furbearers since lynx are classified as a big game

Figure 4: Landscape Potential

Present Disturbance

Wolf (left), Fisher (right)


species and are subject to hound hunting as well6.

Lynx can also range very widely, easily covering

multiple trap line areas. They are naturally

vulnerable to periodic die-offs and population

fluctuations, and population persistence is greatly

dependent on successful dispersal. Lynx are

relatively specialized with respect to prey and

habitat conditions, and the best habitat often

occurs in association with extensive areas of

relatively subdued terrain having specific climatic

and forest attributes. Within ecologically diverse

regions such as the Peace Break, such landscapes

tend to be naturally disjunct in distribution.

For lynx, population fragmentation is further

exacerbated by human accessibility both within

core habitat areas and within the connective

landscapes through which lynx move and which

they occupy on at least an ephemeral basis.

Within the Peace Break region, the loss of

landscape effectiveness for lynx is notable at

both the regional (10% currently) and local scale

(16%). Fragmentation is also an issue, but more

so at the local scale where both moderate and

marginal habitats are being transformed to and

interspersed with highly suboptimal conditions.

Wolverine Wolverines do not rely on a narrow range

of habitat conditions as do lynx and fisher.

Moreover, wolverine population distribution

tends to be associated with rugged and relatively

high elevation landscapes, especially where the

snowpack consistently persists well into May.

Hence, patterns of cumulative human influence

do not impact wolverine to the degree observed

for several of the other focal species. However,

wolverine occur at very low densities and exhibit

massive home ranges. Relatively minor levels of

human accessibility can put regional populations

at risk without de facto protection from harvest.

This is reflected in results that indicate a great

loss in both regional (46% currently) and local

(54% currently) landscape effectiveness for

wolverines. With respect to fragmentation, the

projected trend is reduced continuity of highest


Present Disturbance

Lynx (left), Wolverine (right)


quality landscapes and increased interspersion of

moderate and marginal conditions.

Grizzly Bear The relationship between grizzly bear landscape

occupancy/distribution and cumulative human

impacts can be characterized in terms of both

mortality risk and behavioural displacement

from otherwise suitable habitat. Mortality risk

is the more important impact and results from

both intentional killing of bears as well as killing

resulting from conflict situations. Such situations

are particularly prevalent among ungulate

hunters carrying firearms, but management

removals within landscapes that have moderate

levels of human use are also common.

While underlying densities may vary, grizzly

bears are potentially widespread in distribution

and rarely can persist in close association with

people. Among the suite of focal species, grizzly

bears are subject to significant impact resulting

from cumulative effects of increasing landscape

accessibility. At present, landscape effectiveness

is reduced by 25% and 36% at regional and local

scales respectively, and is likely to fall by a total

reduction of at least 42% and 44% in the future.

Population fragmentation is also a major concern,

with landscapes of both high and moderate

quality being fractured and interspersed with

marginal to highly suboptimal conditions.

Caribou For woodland caribou, cumulative human

accessibility as modeled for this assessment may

function directly to limit caribou population

distribution and connectivity through human-

caused mortality and displacement effects. But

increasing accessibility is also indicative of

landscape change resulting in dominant forest

conditions incompatible with caribou habitat

requirements and likely contributing to increased

predation risk. Current reductions of 22% and

27% landscape effectiveness at regional and local

scales respectively are projected to be reduced

further to at least 31% and 37% in the future.

These numbers are likely conservative since the


Present Disturbance

Grizzly Bear (left),

Caribou (right)


analysis can only account for human influence

from access and not habitat change directly.

At the regional scale, the highest quality

landscapes are being fractured and interspersed

with marginal conditions, and this trend is

projected to continue. These analysis results

support the current observation that much

of the Peace Break assessment area currently

supports relatively small and disjunct caribou

herds. Moreover, without proactive conservation

measures, fragmentation among the larger

regional population is likely to be exacerbated

given the future trend of human activity and

development.

Hydro-Electric ImpoundmentsAmong the wide-ranging focal species considered

in this assessment, fishers have the greatest

potential to suffer major loss of occupied

landscapes entirely due to flooding for hydro-

electric impoundment. The loss of biologically-

productive and seasonally-important riparian

and floodplain habitats is also undoubtedly

significant for other focal species. But it is the

effect of landscape flooding on the movements

Current LossProjected Future LossRemaining

Landscape E�ectiveness - Regional Change

GrizzlyBear

0%

25%

50%

75%

100%

Wolf Wolverine Lynx Fisher Caribou

Current LossProjected Future LossRemaining

Landscape E�ectiveness - Local Change

GrizzlyBear

0%

25%

50%

75%

100%

Wolf Wolverine Lynx Fisher Caribou

Figure 5: Estimated

proportional reduction in

regional (top) and local

(bottom) landscape effectiveness

(relative to maximum

potential) among wide-ranging

focal species given current and

projected year 2036 scenarios.


of individuals and hence the connectivity of the

larger population that is of particular concern.

For all focal species considered, major reservoirs

will obviously reduce landscape permeability

dramatically. Such large water bodies can be

expected to contribute to measureable breaks in

demographic and possibly genetic connectivity.

However, these features are unlikely to constitute

absolute barriers. All of the wide-ranging focal

species considered in this assessment have known

potential to move across water bodies (swim or

traverse ice) similar to the existing and proposed

impoundments of the Peace River (see full report

for details).

Understanding the potential for each species to

move across major water bodies is relevant to

recommendations on mitigating existing and any

future reservoirs. In particular, the potential for

individuals to traverse such impoundments likely

depends on the proximity and effectiveness of

core habitat areas. Mitigation strategies should

consider the potential for enhancements to

habitat productivity and security in landscapes

that have high inherent potential for given

species and are adjacent to existing or proposed

impoundments.

The Issue of Connectivity

Ecological connectivity is a fundamental principle in the conservation of wildlife,

ecosystems and biodiversity7. In a general sense, all animal and plant populations

are shaped by, and persist because of, spatial connections. Habitat connections are

needed for mobile animals to move through and survive within resident home ranges.

At broader scales, landscape linkages allow individuals to move among core habitat

areas, providing stability to regional populations and allowing range peripheries

to be occupied through periodic or continual augmentation. The resulting genetic

flow across large connected populations also contributes to localized adaptability to

a changing environment and helps to ensure that only genes beneficial to individual

fitness are expressed.

The threat to ecological connectivity is greatly influenced by the spatial pattern

of human development. For example, highways often concentrate settlement and

development in a manner that can pose a significant threat to ecological connectivity

by influencing both animal movements and mortality risk8. The nature of these or

other localized impacts depends on the current potential to support a connected

population across the larger region given existing biophysical and human conditions.

Hence, maintaining and enhancing connectivity across regional landscapes requires

consideration of specific movement options as well as landscape management for

habitat effectiveness and security.


Conclusions & Recommendations

Cumulative EffectsMy intent in this assessment has been to evaluate

cumulative human influence on landscape

effectiveness and connectivity for a suite of

wide-ranging species. For each species, my

report describes the magnitude of development

impacts and compares past, present and potential

future scenarios. Current and projected impacts

for each species are a function of (1) inherent

habitat requirements, (2) different sensitivities to

human activities, and (3) resulting potential for

population distribution and connectivity.

Although the nature of impacts varies among

species, I judge from assessment results that net

cumulative impacts at both the regional and local

scales are highly significant for all species. While

it is not possible to know the specific threshold

of population persistence for a given species at

either assessment scale, that point is undoubtedly

exceeded in many landscapes and resulting

population fragmentation is an obvious threat.

Given the current trend, this fragmentation

is likely to increase, further reducing regional

population stability and viability for the species

considered, regardless of whether Site C is

constructed.

Planning and Management for ConservationThere does, however, appear to exist for each

species at least some secure and effective habitat

areas that are likely to sustain productive

individuals and connected population cores. The

protection and enhancement or recovery of such

known or potential core areas and connections

is central to conservation planning for these

species. This end is most likely to be achieved

through the flexible application of available

conservation mechanisms, such as new protected

areas and special management regimes, that may

involve partnerships among government, non-

government, industry and private organizations

and individuals.

While the distribution of private land is extensive

in the Peace Break region, the majority of lands

with reasonable value to the wide-ranging focal

species considered in the report is under public

ownership and therefore available for protective

management. Here, the conservation of healthy

and naturally distributed wildlife populations

is an important mandate of British Columbia

environment and natural resource ministries.

Thus, halting and potentially reversing the

recent trend of cumulative human impacts on

focal species within the Peace Break region

is a reasonable goal. But, effective long-term

conservation is a less likely outcome if Site C is to

proceed.

Regardless of the decision on Site C, offsetting

and moving toward the reversal of existing and

potential-future cumulative human impacts

within the Peace Break region will require

focused mitigation and conservation planning at

local to regional scales. The species considered

in the assessment are effective indicators for

conservation of complete terrestrial communities

and related ecological processes, especially at

broad scales.

The modeling and analytical outputs provided

in the report can assist in the planning process,


particularly in defining landscapes where

specific mitigations and/or conservation zoning

are likely to be most effective. Planning efforts

should focus on the protection and enhancement

of landscape conditions that facilitate core

population areas appropriately buffered from

negative human impacts. These core areas

will most effectively anchor a resilient regional

population where connecting linkage zones

are also protected, enhanced and/or restored.

Central to such efforts will be the management

and reduction of human access in such core areas

(especially motorized). But habitat management

that is appropriate to the local ecosystems

and their regime of natural disturbance is also

important. Planning for such enhancements

with species-specific or biodiversity objectives

should be carried out in concert with human-use

management to avoid the promotion of attractive

population “sinks” with high levels of mortality

risk.

Landscape Fractures and LinkagesIn managing and conserving broad-scale

population connectivity for wide-ranging

species, conservation strategies to address major

fracture zones are of great importance. Such

fractures are often associated with highways

and the linear pattern of human development

along them especially where associated with

private land. This highway-fracture association

is apparent within the Peace Break region. But

it is also important to note that the course of the

Peace River and its hydroelectric impoundments,

including the Peace Reach of the Williston

Reservoir, also represent a present or emerging

population fracture for most of the species

considered in the report. Here, connectivity

may be best conserved and/or enhanced through

increased protection of adjacent landscapes

from further human access and impacts. Many

human impacts, including impoundments,

do not necessarily constitute absolute barriers

to movement. Such movements, however

infrequent, will be much more likely if adjacent

landscapes are attractive, secure and productive

for a given species. Moreover, any opportunities

that exist to secure and potentially enhance

movement opportunities through non-flooded

landscapes spanning the Peace Valley should be

of high conservation priority. This should include

a potential linkage zone through lands between

the W.A.C. Bennett Dam and the Dinosaur

Reservoir, southeast to northeast of the Peace

Arm of the Williston Reservoir. It should be

noted that much work toward the promotion of

an ecological connectivity network for the Peace

Lowlands Ecosection is completed and available9.

The Need for Reliable Information and KnowledgeThere is an obvious paucity of information

derived from local research or inventory for most

of the species considered in the report. Such

local understanding and/or survey or monitoring

data would greatly contribute to the modeling of

species occurrence, distribution and connectivity

and in evaluating current impacts and trends.

For example, despite the availability of highly

effective survey methods, there is virtually no

information on grizzly bear abundance and

distribution within the Peace Break relative

to many other regions of the province. In the

absence of such information to reliably inform

modeling and population viability analyses, I

recommend that the precautionary principle


be applied in the consideration of the Site C

project and other developments that are likely to

exacerbate the adverse cumulative impacts that

presently pervade the region.

Cumulative Effects and Proponent ResponsibilityMaintaining viable and naturally distributed

populations of native wildlife is consistent with

public policy in British Columbia10. It follows

that acceptable landscape-specific thresholds of

cumulative effects (quantifiably estimated) be

established on behalf of the public. Against these

standards, it is appropriate that development

proponents individually or collectively shoulder

the responsibility for demonstrating that the

cumulative impact to long-term persistence and

viability of the wide-ranging focal species is not

excessive or can be effectively mitigated.

Continental Significance - the Y2Y ContextThe Y2Y region includes the Rocky Mountains

and associated ranges of western North America

stretching from the greater Yellowstone

ecosystem to the Yukon’s Peel River watershed.

These mountain ranges are globally significant

in their large component of wild lands and the

relatively continuous and connected populations

of most native large mammals that are supported.

However, without proactive conservation

planning, a regional fracture of ecologically

connected landscapes may eventually emerge

due to current and projected levels of cumulative

human impacts across the Peace Break region.

The consequences of this scenario are of potential

significance at a continental scale.

The Peace River valley,

running east-west through the

heart of the region, supports

abundant and diverse wildlife

populations. (photo: Larry

Peterson)


Primary Points of Conclusion and Recommendations• For wide-ranging species, evaluation and

mitigation of cumulative human impacts is most

relevant at broad scales of regional population

distribution and should consider the potential for

landscape occupancy, productivity and population

connectivity.

• I judge the net cumulative impacts at both

the regional and local assessment scales to be

significant for all wide-ranging terrestrial species

considered.

• A threshold of population persistence has

undoubtedly been exceeded in many landscapes

and resulting population fragmentation is a threat.

• The direct and indirect impacts of Site C hydro-

electric development and impoundment will

further erode the potential for local and regional

landscapes to support the wide-ranging species

considered herein.

• Bull trout and Arctic grayling fish are also under

pressure from a number of inter-related impacts

within the Peace Break region. The Site C

development will clearly impact these species in

different ways but the net impact and the nature

and extent of planned mitigation is unclear (see full

report for background description of impacts on

fish species).

• Projected human population and development

trends suggest that the stability and viability of focal

species populations may be further compromised in

the future without proactive conservation planning.

As a result, already vulnerable populations may be

driven even closer to local extirpation.

• There may be opportunities for increased

protection of some landscapes, contributing to

the enhancement and/or recovery of secure and

effective habitat areas for multiple species. These

should focus on population cores and important

linkage zones.

• Management and reduction of motorized

human access is central to effective conservation

planning. But habitat management appropriate

to local ecosystems and associated regimes of

natural disturbance is also important. Habitat

enhancement should be planned in concert with

human-use management to avoid the potential

for localized conflict with people and/or increased

mortality among focal species.

• Special attention should be given to measures that

can enhance habitat effectiveness and security

adjacent to potential population fractures through

which some movement by a given species is

possible and desirable. The landscape directly east

of the W.A.C. Bennett Dam that is not subject to

flooding should be of high conservation priority as

a multi-species linkage zone.

• Given current development trends and associated

cumulative effects, the Peace Break Region may

eventually constitute an ecological fracture within

the Y2Y region that is significant at a continental

scale.


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